javax.servlet.jsp.tagext

Interface Tag

All Superinterfaces:

JspTag

All Known Subinterfaces:

BodyTag, IterationTag, LoopTag

All Known Implementing Classes:

BodyTagSupport, BundleTag, BundleTag, CatchTag, ChooseTag, ConditionalTagSupport, CoreForEachTag, CoreForTokensTag, CoreImportTag, CoreOutTag, CoreParamTag, CoreParamTag, CoreRedirectTag, CoreSetTag, CoreSetTag, CoreUrlTag, CoreWhenTag, FmtParamTag, FmtParamTag, FmtParseDateTag, FmtParseNumberTag, FmtRequestEncodingTag, FmtSetTimeZoneTag, FmtTimeZoneTag, FmtTimeZoneTag, ForEachTag, FormatDateTag, FormatDateTag, FormatNumberTag, FormatNumberTag, ForTokensTag, I18NSupport, IfTag, IfTag, ImportTag, IntegerLoopSupportTag, IteratorLoopSupportTag, JspTagFileSupport, LoopTagSupport, MessageTag, MessageTag, OtherwiseTag, OutTag, ParseDateTag, ParseNumberTag, RedirectTag, RemoveTag, RequestEncodingTag, SetBundleTag, SetBundleTag, SetLocaleTag, SetLocaleTag, SetTimeZoneTag, SqlDateParamTag, SqlDateParamTag, SqlParamTag, SqlParamTag, SqlQueryTag, SqlQueryTag, SqlSetDataSourceTag, SqlSetDataSourceTag, SqlTransactionTag, SqlTransactionTag, SqlUpdateTag, SqlUpdateTag, TagAdapter, TagSupport, UrlTag, WhenTag, XmlForEachTag, XmlIfTag, XmlOutTag, XmlOutTag, XmlParamTag, XmlParamTag, XmlParseTag, XmlParseTag, XmlSetTag, XmlTransformTag, XmlTransformTag, XmlWhenTag

public interface Tag
extends JspTag

Tags are Java classes implementing JSP Tag extensions. The class must have a null argument public constructor and implement the tag attribute as setXXX methods, following the Beans spec.

 MyTag tag = new MyTag();

 tag.setPageContext(page);
 tag.setParent(...);
 tag.setFoo(...);
 tag.setBar(...);
 if (tag.doStartTag() == EVAL_BODY_INCLUDE) {
   ...
 }
 if (tag.doEndTag() == SKIP_PAGE)
   return;
 ...
 tag.setParent(...);
 tag.setFoo(...);
 if (tag.doStartTag() == EVAL_BODY_INCLUDE) {
   ...
 }
 if (tag.doEndTag() == SKIP_PAGE)
   return;
 ...
 tag.release();
 

Field Summary

Fields

Modifier and Type	Field and Description
static int	EVAL_BODY_INCLUDE
static int	EVAL_PAGE
static int	SKIP_BODY
static int	SKIP_PAGE

Method Summary

Modifier and Type	Method and Description
int	doEndTag() Callback to handle the end of a tag.
int	doStartTag() Callback to handle the start of a tag.
Tag	getParent() Returns the containing tag.
void	release() Cleans up the tag at the end of the page.
void	setPageContext(PageContext page) Sets the page context of this page.
void	setParent(Tag t) Sets the containing tag.

Field Detail

SKIP_BODY

static final int SKIP_BODY

See Also:

Constant Field Values

EVAL_BODY_INCLUDE

static final int EVAL_BODY_INCLUDE

See Also:

Constant Field Values

SKIP_PAGE

static final int SKIP_PAGE

See Also:

Constant Field Values

EVAL_PAGE

static final int EVAL_PAGE

See Also:

Constant Field Values

Method Detail

setPageContext

void setPageContext(PageContext page)

Sets the page context of this page.

setParent

void setParent(Tag t)

Sets the containing tag.

getParent

Tag getParent()

Returns the containing tag.

doStartTag

int doStartTag()
        throws JspException

Callback to handle the start of a tag.

doStartTag can assume setPageContext, setParent, and all tag attribute properties have been called.

Returns:

SKIP_BODY to ignore the body and EVAL_BODY_INCLUDE to evaluate the body.

Throws:

JspException

doEndTag

int doEndTag()
      throws JspException

Callback to handle the end of a tag.

Returns:

SKIP_PAGE to skip the rest of the page and EVAL_PAGE to continue with the rest of the page.

Throws:

JspException

release

void release()

Cleans up the tag at the end of the page. The same tag instance might be reused for multiple tags in the page.